How did “chopped liver” come to mean “of little value”?

Question

Where did the phrase "chopped liver" originate?

Why does it mean "of little value"?

Answer 1

According to the Phrase Finder, chopped liver is always served as a side dish, never as a main dish. It therefore makes a good metaphor for someone who's being treated as unimportant or dispensable.

Answer 2

Wikipedia has a page for Chopped Liver, which also explains the origin of it as an expression.

Since eating chopped liver may not be appreciated by everyone, the Jewish English expression "What am I, chopped liver?", signifies frustration or anger at being ignored on a social level.

An alternative explanation for the etymology of the "What am I, chopped liver?" expression is that chopped liver was traditionally served as a side dish rather than a main course. The phrase, therefore may have originally meant to express a feeling of being overlooked, as a "side dish."

A similar reference aired in 1963 on The Dick Van Dyke Show on an episode titled "Jilting the Jilter" at the Internet Movie Database. Sally Rogers, played by Rose Marie, is asked by a "second-rate comedian" Fred White, played by Guy Marks, "What do you think you are your majesty, chopped chicken liver?"

Answer 3

Found its use back to a 1949 publication, The Curtain Never Falls by comedian Joey Adams (née Abramowitz):